1. Technical Field
This invention relates generally to inductor type rotating dynamoelectric machines and, more specifically, to an improved support structure for the stator assembly of such machines.
2. Background Art
Inductor type dynamoelectric machines have been employed, in the past, to realize high-speed operation, particularly for electrical generation. Such machines are generally characterized by a stator which includes both AC armature and DC excitation coils, surrounding a coil-less rotor. Since there are no rotating field or armature coils in this type of dynamoelectric machine, slip rings, brushes and associated connections, common to machines having rotating windings, may be entirely eliminated. This feature, coupled with the typical solid construction of the machine rotor, makes the inductor machine particularly adaptable to high rotational speed applications.
One known version of an inductor type dynamoelectric machine, employs a circumferentially distributed arrangement of "C" or "U" shaped armature elements surrounding a generally cylindrical field coil which in turn encloses a transverse pole magnetic rotor. U.S. Pat. Nos. 437,501, and 2,509,097 and 3,912,958 describe earlier machines of this general design. Such machines typically employed frame mounted hardware for supporting the components of the stator and suffered from deficiencies attendent to this construction.
A more recent version of such an inductor type machine is disclosed in commonly owned U.S. Pat. No. 4,786,834 issued Nov. 22, 1988 in the name of James J. Grant et al. The improvement described therein encompasses a spool-like support structure for supporting the field winding and armature elements from inside and for accurately positioning the armature elements. The spool-like structure is made of non-magnetic material and has a hollow, elongated central portion extending concentrically about a longitudinal axis. This central portion supports a field coil and defines an interior longitudinal passageway for accommodating the insertion of a coaxial rotor. At each end of the central portion, end portions extend radially outward therefrom. Each of these end portions is preferably provided with radially oriented grooves in its axially outermost surface. The grooves are configured to receive and orient legs of generally U-shaped armature core elements arrayed in a circumferentially distributed pattern about the periphery of the spool-like structure. The end portions of the spool-like structure are axially spaced and radially dimensioned, and the grooves in the outer face of each end portion are angularly spaced so as to precisely position the armature elements in three orthogonal directions.
The earlier application also contemplates, for cooling purposes, the provision of cooling ports in the central portion of the spool-like structure. These ports are located near the ends of the central portion and advantageously communicate with extended recesses in the surface of a rotor mounted for rotation within the central portion. The rotor acts as an impeller and centrifugally propels cooling fluid through said cooling ports and into the vicinity of the field winding and armature coils.
Other features, advantages and benefits of this recently developed, highly acclaimed dynamoelectric machine are detailed in U.S. Pat. No. 4,786,834 issued Nov. 22, 1988, the disclosure of which is incorporated by reference herein.
In practice, the end portions of the spool-like stator support have previously been fabricated as machined one piece parts. These machined parts, although satisfactory in operation, are relatively difficult, time-consuming and accordingly, expensive to manufacture. Also, it would be desirable to be able to further reduce stray flux and eddy current losses in such end pieces, to incorporate greater flexibility in their design, and to provide for ventilation through the end pieces, thereby simplifying fabrication of the central portion of the spool-like support structure.